Superionic Phase Transition in Rb4LiH3(SeO4)4 Single Crystals |
| M. Połomska, B. Hilczer, J. Wolak Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17/19, 60-179 Poznań, Poland and A. Pietraszko Institute of Low Temperature Physics and Structural Research, Polish Academy of Sciences, Okólna 1, 50-950 Wrocław, Poland |
| Received: November 30, 1993; in final form: March 1, 1994 |
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| Derivatographic, dielectric and complex impedance studies of Rb4LiH3(SeO4)4 crystals revealed a superionic phase transition at Ts ≈ 448 K. The bulk conductivity rises from 10-6 to 10-4 (Ωm)-1 at Ts, and the activation energy of conductivity in the direction of crystal axes a and b (where a = b for tetragonal symmetry) Wa = Wb decreases from 0.94 eV in the low temperature phase to the value of 0.27 eV at T > Ts. The analysis of the results of X-ray studies at room temperature and at 450 K indicates that the fast ion transport, characterized by low activation energy, is related to the delocalization of the H2 protons in the O(12)-H2-O(24) bonds linking the Se(1)O4 and Se(2)O4 tetrahedra. The "cogwheel" mechanism is suggested to be involved in the fast proton transport. |
| DOI: 10.12693/APhysPolA.85.825 PACS numbers: 61.50.Em, 62.20.Dc, 77.22.Gm |